Lamp base



Sept. 24, 19460 H. K. RlcHARbsoN LAME BASE Filed uai-ch 25, 1937 MM; W

ATTORNEY Patented Sept. 24, 1946 2,407,998 IJAMP BASE Henry K. Richardson,

to Westinghouse E Bloomfield, N. l, assignor lectric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 25, 1937, Serial No. 132,956

14 Claims.

This invention relates to the manufacture of electrical devices such as high wa-ttage incandescent electric lamps, power tubes, rectifiers, or other devices where metal contact elements are employed for the passage of heavy currents, and is a continuation-in-part of my application Serial No. 692,587, filed October 7, 1933, now Patent No. 2,075,057, dated March 30, 1937 When making a high-wattage incandescent electric lamp, as shown for example, in the lviassie Patent No. 1,869,572, or the Howe Patent N 0. 2,010,084, it is desirable from an operative and practical standpoint to provide relatively large metallic contact pins and considerable difiiculty has heretofore been encountered in sealing the pins in the glass wall of the bulb which forms part of the device.

It has been proposed to provide tubular contacts, termed thinible seals, preferably closed at one end and having the opposite end provided with a thin-edged funnel shaped opening. These pins are sealed to the wall of a bulb by first beading the edges of the open ends with glass and then heating by means of gas flames to seal the head to the edges of suitably disposed openings.

It is an object of the present invention to provide an improved form of base for a vacuum device.

Another object of the invention is to provide a base with contact members held by internal seals.

A further object of the invention is to provide a base with means for projecting into contact members for consolidation therewith to hold said members rigid,

Other objects and advantages of the invention will be more clearly understood from the following description together with the accompanying drawing in which,

Fig. 1 shows a portion of a bulb, partly in section, with contacts or thirnbles sealed therein in accordance with the present invention;

Fig. 2 shows apparatus for holding a thimble in position to be sealed to a bulb wall and means for heating the glass;

Fig. 3 is a view similar to Fig. 2, but shows the glass after it has been softened and sealed to the edge of a contact member; and

Fig. 4 is a modified form of apparatus for sealing a thimble to a bulb, in which the heater is disposed within the end of the thimble, and in which the thimble connects with the bulb in a slightly diiferent way.

In devices of the character to which the present invention is most applicable, a cup-shaped comparatively heavy preformed base portion ill of glass or other vitreous material is provided. This cup comprises a bottom wall, a peripheral flange, and is provided with contacts or thimbles i i. It is sealed along edge E2 to a bulb l indicated in dotted lines, and adapted to enclose the light source or other energy-translating unit. The cup may be provided with an exhaust tube i l, through which the bulb may be evacuated in the usual manner. Usually the cup is provided with rigid metal support members or lead-in conductors i l, to which electrodes or resistance elements such as tungsten filaments, which be like the filanient l and associated support members 2 and 3 of the Massie patent, or the filament 2 and associated support members 3 and 4 of the Howe patent, above referred to, are secured. The cup may, therefore, be constructed to include the internal structure or operating elements of the device and aconvenient method is, therefore, had for properly mounting the elements and for locating them within the bulb. When the cup is fused to the bulb the device is complete for the sealing-off operation.

As above mentioned, it has heretofore been proposed to provide the metal thimbles with glass layers or beads to facilitate their gas-tight union with the bulb wall. In the present case, however, this beading is dispensed with.

The wall 55 of the cup is provided with apertures is of any desired number. lhe selected embodiment of the invention includes two such apertures, since two contacts are to be used. Each aperture is provided with an outwardly extending tapered hollow boss or extension ll. This boss is so proportioned that it just enters and engages the inner surface adjacent to a tapered edge 253 of the enlarged portion lb of a thim'ble El. This enlarged portion of the thimble forms a surrounding flared skirt and is integral with a tubular cylindrical portion iii which serves as the contact proper and enters a socket for the passage of electrical energy through the device when in operation. The side of each boss ll is preferably about as thick as the wall l5, so that the hole through the enlarged portion of the thimble, defined by the tapered edge fll, is restricted, as shown, to correspond approximately with the interior of the tubular cylindrical portion ill, whereby a strong connection with the thimble is provided, while allowing for the reception of a lead in wire l5. That portion of each conductor l l, adjacent the connection with its thimble ll, forms, with said thimble, a rigid metal contact terminal extending through its receiving hole I6. Ihe slrirt portion 18, because of its thinness, as illustrated, has elastic properties, permitting slight relative rocking of the contact member II with respect to the base ID.

A support or socket 2! having apertures or pockets 22 may be provided to hold each contact element in position so that the boss 11 may be positioned, as shown in Fig. 2. In accordance with the present invention a local heat zone is provided to soften the wall and glass boss I1 and cause the latter to wet or stick to the edge 23 of the enlarged portion iii of the thimble, while at the same time softening the wall l5 sufficientl to allow the edge to be embedded or sealed therein, as illustrated in Fig. 3. In the present construction a heat zone is created by means of a resistance element 22' in the form' of a helical coil which surrounds the tapered edge 2i! and the contacting glass boss H. An insulative baffle 23 may be provided to confine the H heat for the purpose intended when current passes through the coil. Any suitable source of current supply may be used and a switch 24 may be provided to open and close a circuit including conductors 25 and 26, attached to opposite ends of the coil or resistance element 22'. Some al ternative source of heat may, of course, be employed, for example, an oxy-hydrogen flame. When the respective parts are in position and the glass boss has been heated to a sufliciently plastic state, a member 21 is moved downwardly against the inner edge of the aperture l8 to firm- 1y press the glass against the edge 20, so that the sharp edge of the enlarged thimble portion engages the outer surface of the wall I5, is embedded therein, and effects a gas-tight seal.

The member 21 is disposed with its vertical axis in alignment with the vertical axis of the contact member so that as pressure is applied to the member the contact pin is aligned with the axial line of the tubular boss or extension ll. Thus, as heat is applied to soften the glass to permit it to flow onto the inner surface of the contact, the member 21, in conjunction with the support for the contact pin, maintains the proper perpendicular relation of the pin with the Wall [5.

In cases where exceptionally large contact members are employed, a heater element 21 (see Fig. 4) may be disposed within the confines of an edge 28 of a thimble 29 and a glass boss 35. In this case a heater coil 32 may be carried on a sleeve 33, one end 34 being electrically connected to the sleeve. The other end 35 of the coil may be connected to a conductive member 36 suitably insulated from the sleeve 33. Electrical energy may be supplied from any suitable source and. a switch 3'1 may be employed to control a flow of current through conductors 38 and 39, connected to the sleeve 33 and member 35, respectively. When current flows through the heater element, the glass boss 3| is rendered plastic and wets the edge 28 and a gas-tight seal is produced. Obviously, if found desirable, the structure shown in Fig. 4 may be provided with an external heater coil to provide a surrounding zone of heat to facilitate the sealing operation.

In the present embodiment, the boss 3! does not extend directly from the normally horizontal wall portion l5, but is connected thereto by an approximately conical portion 40, and the edge 28 of the thimble 29 is not embedded in the wall l5, as in the previous embodiment, but merely extends to the conical portion 40. However, it will be understood that, if desired, a large thimble 29 may be secured to a bulb It) by having its 4 edge embedded or sealed in the wall 15' thereof, as in the embodiment of Figs. 1, 2, and 3, the boss 3! for that purpose extending from said wall like the boss I! of Figs. 1, 2, and 3.

It will also be understood that, although the embodiment of Figs. 1, 2, and 3 shows the enlarged portion l8 of a thimble ll secured to the wall IS with its edge portion 20 embedded or sealed therein, yet the Wall 15 may have its boss i1 formed like the boss 3| of Fig. 4; that is, secured to it by a conical portion, and the sharp or tapering edge portion 20 need only be secured to the outer surface of the boss I1 and not embedded or sealed in the wall [5.

Whether or not a connection as shown in Figs. 1, 2, and 3 or as shown in Fig. 4, is employed, may depend on the kind of glass used. If Pyrex (C. Gui-7741) is employed, in which the coefficient of expansion between 20 and 320 C. is about 32 10", it is desirable to employ the connection illustrated in Figs. 1, 2, and 3, in order to avoid cracks due to shearing action between the sides oi the enlarged portion 18 of the thimble l l and the boss l1. However, when No. 705 glass is employed, in which the coefficient of expansion is about 46 10 either type of connection may be employed without any trouble.

Although preferred embodiments of the invention are shown and described herein, it is to be understood that modifications may be made therein without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim:

1. An electrical devic comprising a glass vessel, an aperture leading from said vessel and defined by a hollow tapered boss extending from a wall thereof, and a metal contact member secured to said boss, said member comprising a hollow, cylindrical portion closed at its outer end, shouldered at its inner end, serving as the contact proper, and adapted to receive a lead-in wire from said vessel through said aperture, and an enlarged portion extending toward said vessel from said shouldered portion, the sides of said enlarged portion decreasing in thickness from said shouldered portion to a sharp edge, said enlarged portion flaring toward said vessel, fitting over said tapered boss and sealed only to the exterior thereof, the sharp edge of said enlarged portion ngaging said wall which is continued outwardly therefrom at an angle to said contact member so as to effect a gas-tight seal.

2. An electrical device comprising a glass vessel, tubular bosses extending from a wall of said vessel. and cylindrical metal contact members having shoulders from which enlarged flaring portions extend into engagement with said wall and are disposed around and sealed to the exterior of said bosses to effect a gas-tight seal.

3. An electrical device comprising a glass vessel, tubular bosses extending from a wall of said vessel, and tubular contact members having closed outer ends, intermediate shoulders, and enlarged portions flaring toward said vessel, the walls of said enlarged portions tapering to thin edges, fitting over said bosses, extending to said wall, and sealed to the outer surfaces of said bosses.

4. A base for a lamp bulb comprising a glass cup defined by a bottom wall and peripheral flange, tapered hollow extensions on said wall, and tubular metal contact members having shoulders and flaring enlarged portions extending from said shoulders, said enlarged portions fitting said tapered extensions, engaging said wall, and sealed to the outer surfaces of said extensions.

5. An electrical device having a vitreous wall provided with apertured portions, and metal contact members, each extending in a direction substantially normal to the plane of an apertured portion, comprising a contact proper and a skirt portion extending therefrom, flaring toward said wall, and having a sharp edge portion surroundand with the sharp edge portion sealed thereto to efiect a gas-tight union.

6. An electrical device having a vitreous wall sel, a wall of cylindrical metal contact members having shoulders from which enlarged flaring sharp portions extend into engagement with said wall, and are disposed with said sharp portions sealed around the apertures to effect gas-tight union.

10. An electrical device comprising a glass vessel, a Wall of said vessel having apertures and tubular contact members having closed outer ends, intermediate shoulders, and enlarged portions flaring toward said vessel, the walls of said enlarged portions tapering to thin edges sealed to the outer surface of said vessel around the apertures.

11. A base for a lamp comprising a glass cup defined by a bottom wall and a peripheral flange,

apertures and sealed to said wall.

12. A metal contact terminal device for a bulb wall base comprising a contact proper, a lead-in conductor portion adapted to extend through an aperture in said base, and a flared skirt taperbetween said device and base.

13. An electrical energy translation device comprising a vitreous envelope having openings therein, a plurality of metal contact terminals each comprising lead-in conductor portions passing through one of said openings, a contact propa flared skirt extending therefrom, each terminals having suflicient rigidity to support the device.

14. An electrical device comprising a vitreous vessel, a Wall of said vessel being formed with the sharp-edge a gas-tight seal.

HENRY K. RICHARDSON. 

